Rain to start this weekend leads to a dramatic pattern change with anomalous ridging taking place by late in the forecast period. Temperatures throughout the period range from a few degrees above normal in the mid-40s to the mid-50s by Monday. The warmth continues into the middle of next week.
Rest of today – mostly cloudy with high temperatures in the mid-40s. A relatively weak coastal low will develop and move towards our area overnight. The best chances for rain are in the early overnight hours. Overnight lows in the mid-30s.
Saturday – rain chances will diminish quite a bit as the core of the low continues exiting to the northeast. Mostly cloudy with high temperatures in the mid-40s. Overnight lows in the the mid-30s. Some snow could mix in overnight as lingering chances for precipitation continue.
Sunday – things will dry out as the low continues to distance itself from us. Mostly sunny with high temperatures in the mid-40s. Overnight lows in the upper-30s.
Monday– the synoptic scale pattern shifts as strong ridging at the mid-levels occurs. This will translate to warm high temperatures in the mid-50s on Monday with mostly sunny skies and southerly flow. Overnight lows in the mid-40s.
Lunar New Year day in New York city will see the passage of a relatively robust storm system. Ahead of this storm, persistently easterly onshore winds could result in some minor coastal flooding. A band of moderate to heavy rain looks like it will sweep through in the afternoon hours. Rain should clear up quickly by the early evening. Temperatures should be above normal with some warm air advection.
My Forecast High: 49°F | Low: 38°F | Max sustained winds: 26 mph | Total precipitation: 0.85″ – verification will come from METAR data for the period between 1AM Saturday and 1AM Sunday (06Z Saturday to 06Z Sunday) at LGA (LaGuardia Airport), and the KLGA Daily Climate Report.
Verification High: 52°F | Low: 38°F | Max sustained winds: 30 mph | Total precipitation: 0.78″ – all around this wasn’t too bad of a forecast. Wind speeds were slightly higher, and coming from the southeast. This could help explain why temperatures broke into the low-50s as this set up would have produced better warm air advection. Got the low temperature spot on. As for precipitation, at first I thought this was going to be a bust because the storm seemed to be moving faster than model data suggested. However, even with rain stopping by around 4pm, enough moderate to heavy rain fell that we went above 0.75″, though not too much over. I’m glad I didn’t buy into a higher precipitation total than 0.85″!
Weather Prediction Center surface forecast for 7AM Saturday
Synoptic Set Up A primary occluded low tracking over the Great Lakes will spawn a secondary coastal low at the triple point between its occluded, warm and cold fronts. The primary low should weaken as it becomes vertically stacked with a 500 mb closed low (depicted below) and slowly consolidate with the secondary low. During the day, the secondary low is forecast to track northeast with the triple point tracking almost directly over NYC by around 7PM.
Ahead of this, we could see some light rain due to isentropic lift north of the surface warm front. Strong lift is expected as the low/triple point tracks closer, and lift will be enhanced by favorable conditions at 300 mb and 500 mb levels. At the 500 mb level, the aforementioned closed low is forecast to cause ample downstream positive vorticity resulting in increased divergence. Further up at the 300 mb level, it appears the left exit region of a powerful jet streak over the Southeastern US will lie south of us, and we’ll be under the right entrance region of a smaller, weaker jet streak. Both these regions will produce increased divergence and enhance lift. SREF probabilities for moderate to strong omega > -6 mb/sec were in the 50%-70% range.
High resolution models suggest a narrow band of moderate to heavy rain during the afternoon hours. A significant low-level jet at 850 mb with winds 45-55 knots and will aid with transporting subtropical moisture northwards. A dry slot works in quickly behind the primary slug of moisture by 7PM – this should cut off precipitation for the most part.
NAM 500 mb heights and vorticity valid 4PM Saturday
NAM forecast 300 mb heights and wind valid 1PM Saturday
High Temperatures Statistical models were in decent agreement, with NAM being the coolest coming in at 46°F. GFS was closer to 50°F and EKDMOS 50th percnetile was 49°F. Erring on the side of being cautious about going warmer than 50°F because of of the proximity of the triple point. If that tracks offshore more, we’d see a switch to westerly winds sooner and would end up being in a cooler airmass. Rain and clouds will also keep things in check. There’s some warm air advection indicated, but also need to keep in mind that sea surface temperatures are only in low-40s offshore around NYC. For these reasons, went the EKDMOS 50th percentile at 49°F.
Low Temperatures The surface and near surface layer start off pretty dry. Evaporational cooling as the column saturates could have potential to keep temps on the cool side. EKDMOS 50th percentile was steady across two runs at 39°F. Statistical models had a spread from NBM at 36°F to GFS with 42°F. I’m going with 38°F because I think evaporational cooling will be a factor overnight.
NAM MOS forecast for KLGA
GFS MOS forecast for KLGA
Max Sustained Winds Seems like winds will mostly driven by synoptic factors, since I don’t see signs of a well-mixed surface layer. However, downard momentum transfer with heavy rains could help bring some of the very fast 850 mb winds to the surface. It’s not hard to imagine sustained winds in excess of 20 knots. Winds coming from the east-northeast and east will be off the water towards LGA, with decent fetch over open water, so edging towards a higher max wind of 26 mph. This matches EKDMOS 50th percentile and is higher than GFS and NAM statistical guidance of 16 and 19 knots respectively.
NAM forecast sounding for KLGA valid 1PM Saturday. The atmospheric column is saturated throughout by this point (dew point temperature in green and environmental temperature in red overlap), meaning precipitation is ongoing. Also note how strong winds are throughout the column.
Total Precipitation Strong lift will accompany the triple point as stated above. A low-level jet is also forecast to set up, creating conditions conducive for heavy rain. However, development of a dry slot is apparent in the early evening – this would put the brakes on precipitation. If that dry slot moves through earlier, bust potential for higher end total precipitation amounts is there. Statistical guidance ranges 0.60″-0.75″ on the low end, up to 1.23″-1.48″ (which would be record-breaking) on the high end. Various ensemble means range from 0.77″-0.94″, which is on the low end of the statistical guidance. Ensembles also showed a fairly tight spread, indicating decent confidence. The ensemble plume mean is close to the average mean of statistical guidance around 0.85″. This seems reasonable as it allows for possibility of heavy rain while still falling squarely within predicted ranges for both statistical and ensemble guidance. SREF probabilities for > 1.00″ of total precipitation aren’t a lock (10%-50%) with a very tight gradient southeast.
This weekend coming up will see a dramatic contrast from last weekend’s record-breaking warmth. Temperatures during the next few days will be average to below normal. Overnight lows in the low-20s for this period. A “warm up” will happen as we enter the warm sector of a passing storm Saturday going into Sunday, but reinforcing cold air arrives to start next week.
Rest of today – partly sunny with strong northwesterly winds. Temperatures will drop from around 50ºF into the low in the mid-20s overnight. A trough extending west from a departing area of low pressure that’s bringing the strong winds may touch off some rain.
Friday – a cold, sunny day with high temperatures starting off in the low-20s and only expected to reach 30ºF under the continuing influence of northwesterly winds .
Saturday – a large storm system will move through. Temperatures starting off in the low-20s will warm into the upper-30s with southerly flow ahead of the main cold front associated with this low. Thermal profiles will support snow to start, with a light accumulation possible before temperatures warm enough at the coast to transition to all rain overnight. Overnight lows aren’t expected to move much, dropping into the mid-30s.
GFS model 500 mb height anomalies for 7AM Monday
GFS model 300 mb heights and winds for 7AM Monday – the orientation of the jets stream mirrors the position of 500 mb height anomalies
Sunday– improving conditions with high temperatures in the upper-30s and partly cloudy skies. Overnight lows in the low-20s as a second and stronger blast of Arctic air flows in behind Saturday’s storm.
The weather story for this weekend in NYC will be the near record-breaking warmth we’ll have with temps at or above 60°F Saturday and Sunday. A storm system sweeps through overnight going into Sunday, and should clear by Sunday afternoon. Behind this, temperatures will drop back to the upper-40s, which is still almost 10ºF above normal for this time of the year! Enjoy this rare occurrence of near record warmth that isn’t accompanied by a washout.
Rest of today – mostly cloudy with high temperatures in the low-50s. A strong area of high pressure offshore southeast of our area will be steadily pumping warm, moist air into the region. Looking at the chart below, you’ll see southerly winds blowing at large angles across temperature contours that increase going south – this is an ideal set up for persistent warm air advection and will set the stage for the warmth we see this weekend. Overnight lows in the mid-40s. With moisture advecting into the area, we could see areas of fog develop overnight.
GFS 2-meter temperature with contours and 10-meter wind barbs.
Saturday – very mild with temperatures in the low-60s. Mostly cloudy with a southerly breeze and some fog possible. Overnight lows in the mid-50s. Rain chances increase particularly late overnight going into Sunday morning.
Sunday – elevated convection could bring a rumble of thunder Sunday morning, with rain chances peaking in the early morning hours. High temperatures should remain quite mild, in the mid-60s (and possibly higher with downsloping westerly winds for a period with clearing skies, following the passage of a prefrontal trough and before a cold front closes in). Overnight lows dropping into the low-40s – which is actually still above normal for what a daytime high temperature should be this time of year.
NAM high resolution model output of 1000-500 mb thickness, surface pressure, and precipitation valid for 5AM Sunday
Monday– high temperatures similar to Friday near 50ºF, partly sunny skies. Overnight lows in the low-30s.
A quick hitting storm system brings possible light snow to the region overnight into Wednesday. High pressure builds behind this storm, with winds shifting to the northwest bringing a cool down midweek. Another storm approaches towards the end of the week. Ahead of this, temperatures surge back above normal, approaching 60°F, as southwesterly winds instigate warm air advection.
Rest of today – increasing clouds with high temperatures in the mid-40s. A coastal low passes east of the area, bringing some potential for light snow accumulations (1″ or so). Precipitation will start off as rain, though, then transition to snow briefly overnight. Overnight lows drop to around 30°F.
Weather Prediction Center surface forecast for 7PM Tuesday
Wednesday – snowfall may be enhanced by a second fast-moving arctic front. Behind this front, high pressure builds. Decreasing clouds, with winds picking up from the west then veering northwest towards overnight hours. High temperatures in the low-40s. Overnight lows will plummet quickly into the upper-20s with an Arctic air mass and northwesterly flow. Winds may gust above 30 mph during the overnight hours.
Thursday – expecting a calm, bright, sunny day with high temperatures in the low-30s, below normal for this time of year. High pressure will be moving right over us during this time. Overnight lows in the low-30s.
GFS model 500 mb height anomalies for 1AM Friday. Note the strong positive height anomaly over the Northeast, with a corresponding strong negative height anomaly over the Rockies.
Friday – high pressure will move offshore to the east, setting up warm southwesterly return flow between the western periphery of the high and an incoming storm system. High temperatures expected in the upper-40s. Temperatures should in fact warm up overnight, through the upper-40s.
The first weekend in the new year starts off wet and mild with a complex storm system moving over the Eastern US. Things will settle down by Sunday with a cool down coming behind this storm system. Temperatures start to rebound early next week. In general, high temperatures will trend above normal for this time of year by 5°F, topping out in the mid-40s or higher.
Rest of today – periods of drizzle during the afternoon before a second round of steadier precipitation possibly later this evening. High temperatures in the low-50s with the warming influence of westerly flow ahead of the second frontal boundary shown below. Overnight lows in the mid-40s.
Saturday – rain chances continue during Saturday. Like Friday though, the best dynamics and moisture for heavy rain seem to bypass NYC itself. This may result in more periodic rainfall on the light side. Onshore flow from the northeast should continue to keep temperatures mild, around 50°F. Overnight lows will drop into the low-30s as the storm clears and winds turn to the north and northwest.
Sunday – a mostly sunny day expected with breezy northwesterly winds. High temperatures cooler, in the low-40s. Overnight lows remain in the low-30s.
Looking ahead into next week, the above normal temperature trend for much of the Eastern US appears to persist.
Monday– high temperatures in the mid-40s with mostly sunny skies and continuing windy conditions. Overnight lows in the low-30s.
A soggy and messy start to the week will give way to a blast of Arctic air, leading to an extended period of below normal high temperatures only in the 30s for the most part. Temperatures do look to rebound over the weekend towards more seasonable levels. The next chance for precipitation happens Wednesday as an arctic front, harbinger of these much colder temperatures, crosses the area and brings possible snow squalls.
Rest of today – periods of rain during the day with high temperatures in the mid-30s. Rain tapers off and ends early this evening as the low pressure responsible for the stormy conditions moves off to the east. Overnight lows drop to around 30°F.
GFS model 500 mb height anomalies for Wednesday at 7PM, note the strong negative height anomaly over the Northeastern US and St. Lawrence Valley
Wednesday – should be a mostly sunny day, though as an arctic front hits us late in the day and in the early evening, a few snow squalls/snow bands could hit. These would be brief in nature but could impinge on visibility, making travel difficult. High temperatures should be similar to today in the mid-30s. Overnight lows will plummet quickly into the upper-teens with an Arctic air mass and northwesterly flow.
Thursday – northwesterly flow continues as strong Arctic high pressure builds. This will keep temperatures only in the upper-20s for highs under mostly sunny skies. Overnight lows in the low-20s.
Weather Prediction Center surface forecast for 7AM Friday
Friday – temperatures moderate a little bit, with highs in the low-30s as the high starts moving east. Overnight lows in the low-20s.
Mild temperatures in the mid-50s are on the way along with long duration drenching rains to start the weekend. Rain tapers off Saturday evening and conditions improve Sunday with a return to more seasonable temperatures in the 40s. A chance of wintry mix or snow is possible late Monday.
Rest of today – mostly cloudy with chances for rain increasing by the afternoon. Steady rain expected overnight. High temperatures around 50°F. Temperatures actually rise overnight with southeasterly onshore flow aiding warm advection.
NAM 2-meter temperature and 10-meter winds at 11PM Friday
NAM precipitable water for 7AM Saturday
Saturday – rain continues through the day Saturday with high temperatures peaking in the mid-50s as a warm front passes and persistent onshore flow from the southeast, backing briefly to the northeast then veering south continuously advects warmer air off the ocean to the area. Overnight lows are a different picture dropping into low-40s as winds turn to the west behind a cold front.
Sunday – as the parent low bringing this rain moves north of the area and continues gathering strength, winds will pick up from the west. This will bring cooler air to the area resulting in highs in the mid-40s under partly sunny skies. Overnight lows continue a cooling trend to about the freezing mark.
Weather Prediction Center surface forecast for 7AM Sunday
Monday– another storm system will impact the area starting late in the day. Temperatures will be cold, topping out in the mid-30s. Precipitation starting late on Monday should begin as snow or a wintry mix given the currently forecast temperature profile. As is the case going into Saturday, a change in wind direction accompanying a warm front should help temperatures actually rise overnight into the upper-30s, allowing precipitation to transition to rain.
Very mild air at the start of the week gives way to a much colder air mass as a cold front finally sweeps through later today. Drenching rains from yesterday should give way to lighter precipitation today, however, with temperatures dropping we could see some light accumulating snow by Wednesday morning. Temperatures will rebound into normal to above normal ranges after a dip into high temperatures in the 30s mid-week.
Rest of today – mostly cloudy with high temperatures peaking in the upper-50s. Long duration southerly flow ahead of an slow moving cold front has brought in a much warmer air mass to the region. Rain chances pick up in the afternoon with the front nearing and continues into the overnight hours with a couple breaks. Behind this front, much colder air rushes in with overnight lows dropping to near freezing. With precipitation continuing, this should allow for a transition to all snow. Light accumulation of around 1″ is possible, though not a lock since the ground has been quite warm for a couple days now with all the rain.
Weather Prediction Center probabilistic forecast for 1″+ accumulation of snow by 7AM Wednesday
Wednesday – snow winding down in the morning. High temperatures in the upper-30s, about 10°F below normal for this time of year. Skies clearing later in the day with overnight lows in the mid-20s.
Thursday – with a chilly start to the day, high temperatures will have a tough time getting out of the low-30s. Mostly sunny otherwise. Overnight lows in the upper-20s.
Friday – high pressure that fills in behind the cold front passing Tuesday and giving us the sunny weather Thursday eventually moves off to the northeast. Onshore flow should help moderate highs into the upper-40s. Rain chances increase with the next storm system – a possible coastal low – moving up overnight. Overnight lows in the mid-40s.
An arctic front swings through today, bringing a blast of cold air behind it going into the weekend. Temperatures will rebound dramatically going into the start of next week with an approaching storm system turning winds to the south. We’ll see high temperatures going from the upper-30s to the mid-50s by Monday.
Rest of today – mostly cloudy with a high temperature in the upper-40s. Chance of rain this evening with the passage of an arctic front. Overnight lows cooling into the low-30s with clearing skies.
Weather Prediction Center surface forecast for 7AM Saturday
Saturday – high pressure builds behind the arctic front bringing sunny skies but a much colder polar airmass with high temperatures struggling to hit 40ºF. Overnight lows drop into the mid-20s.
Sunday – high pressure center moves off to the east, allowing for warmer return flow from the south. This should allow temperatures to be a touch warmer than Saturday, in the low-40s. Overnight lows are expected to bottom out around 40ºF before actually rising due to an incoming storm system turning winds to the south.
GFS model output for 1PM Monday, a low-level jet at 850 mb with winds in excess of 40 knots is evident, along with pretty high values of relative humidity.
Monday– high temperatures continue to climb into the mid-50s with deep layer south-southwesterly winds. Increasing chances for rain as a cold front approaches from the west. Heavy rain is possible given a possible tropical moisture connection. Overnight lows barely moving into the low-50s.
